Life predicting method for rolling bearing, life prediting device, rolling bearing selecting device using life predicing device, program and environment factor determining method

ABSTRACT

To predict a correction rated life at high accuracy. A life predicting device executes step S 1 , step S 2 , step S 4  for inputting specification information including a basic dynamic rated load C and basic static rated load C 0 , step  5  for computing a dynamic equivalent load P based on the specification information. step S 3  for setting a reliability factor a 1 , step S 7  and step S 8  for determining a contact ellipse area S, step S 9  for inputting a foreign substance purchasing diameter d debris  (“debris” means “foreign substance”), step  10  for determining a standardized foreign substance diameter (d debris /{square root}{square root over ( )}S), step S 11  for setting a life correction coefficient a xyz  based on the standardized foreign substance diameter, and step S 6  and step S 12  for calculating a correction rated life L nm  based on the reliability coefficient, the life correction coefficient, the basic dynamic rated load and the dynamic equivalent load and the like.

BACKGROUND OF THE INVENTION

[0001] The present invention concerns a life predicting method for arolling bearing, a life predicting device, a rolling bearing selectingdevice using the life predicting device, a program therefor and anenvironment coefficient determining method.

[0002] A basic rated life L₁₀ of a rolling bearing is defined in JIS B1518: 1992 and, usually, a calculation formula as shown in the followingformula (1) is used.

L ₁₀=(C/P)^(p)  (1)

[0003] in which C represents a basic dynamic rated load of a rollingbearing and P represents a dynamic equivalent load exerting on thebearing. Further, p represents a load index which is set at p=3 in thecase of a ball bearing and p=10/3 in the case of a roller bearing. Thebasic rated life L₁₀ is defined for a case at a reliability of 90%,using a material used generally, for usual manufacturing quality andunder usual working conditions.

[0004] It is noted that in the calculation formula for the basic ratedlife, only the effect of the bearing load on the bearing life is takeninto consideration. In view of the above, the result of the calculationformula for the basic rated life is greatly different from the result oflife in the market at present. This is because the fatigue life has alsobeen improved by the improvement in the bearing steel materials, and theeffect of the lubricant film thickness at the contact portion between abearing ring and a rolling element on the fatigue life has been analyzedby a study on the theory of elastic fluid lubrication in recent years. Acorrection rated life L_(nm) reflecting the effect of them on the lifecalculation formula was proposed as the following formula (2) by using alife correction coefficient a_(xyz) by ISO 281 in February, 2000.

L _(nm) =a ₁ ·a _(xyz) ·L ₁₀  (2)

[0005] Further, the life correction coefficient a_(xyz) is shown by thefollowing equation (3).

a _(xyz) =f(Pu, κ, a _(c))  (3)

[0006] The life correction coefficient a_(xyz) is represented as afunction considering factors such as fatigue limit load Pu, lubricationstate (kinetic viscosity) κ, and environment coefficient (contaminationdegree of lubricant) a_(c). Further, a₁ is a reliability coefficientwhich is described in the following Table 1 and it takes a lower valueas the reliability is improved. TABLE 1 Reliability % L_(na) a₁ 90L_(10a) 1 95 L_(5a) 0.62 96 L_(4a) 0.53 97 L_(3a) 0.44 98 L_(2a) 0.33 99L_(1a) 0.21

[0007] However, among the variables representing the life correctioncoefficient a_(xyz) the fatigue limit load Pu and the lubrication state(kinetic viscosity) κ are considered quantifiable. However, while theweight, size, shape and substance of foreign substance are consideredfor the comtamination degree a_(c) of the lubricant, they are notquantitatively evaluated but merely represent the environmentambiguously. This has resulted in a problem that the life can not bepredicted at high accuracy according to the formula (2).

[0008] The present invention has been achieved taking into considerationfactors of the prior art which had not theretofore been apparent and itis an object thereof to provide a life predicting method for a rollingbearing capable of predicting the life at a high accuracy according tothe formula (2) for calculating a correction rated life, a lifepredicting device, a rolling bearing selecting device using the lifepredicting device, a program therefor and an environment coefficientdetermining method.

SUMMARY OF THE INVENTION

[0009] In one embodiment of the bearing life predicting method for arolling bearing according to the present invention, a basic dynamicrated load C and a basic static rated load C₀ can be calculated, whereinthe correction rated life L_(nm) of a rolling bearing at a reliabilitycoefficient a₁ is calculated according to:

L _(nm) =a ₁ ×a _(xyz)×(C/P)^(p) a _(xyz) ∝f(α)

[0010] where P represents an equivalent load, p represents a load index,a_(xyz) represents a life correction coefficient, and α represents aratio between a typical dimension for a portion of a bearing to be incontact with a mixed foreign substance and a characteristic quantityshowing the size of the mixed foreign substance.

[0011] Thus, the life correction coefficient a_(xyz) can be set inaccordance with the characteristic quantity showing the size of themixed foreign substance and, further, since the value a for the ratiothereof with the typical dimension for the portion of the bearing incontact with the mixed foreign substance is used for the setting, thelife correction coefficient a_(xyz) can be set in accordance with themixed foreign substance not depending on the size of the bearing.

[0012] In a further aspect of the invention, the ratio a is calculatedaccording to:

α=d/{square root}{square root over ( )}S

[0013] where {square root}{square root over ( )}S represents the typicaldimension assuming a typical diameter of the mixed foreign substance asd, and a contact ellipse area in the bearing as S.

[0014] Thus, the value α for the ratio is determined by using a contactellipse area in the bearing and the life correction coefficient a_(xyz)can be set according to the determined value α for the ratio.

[0015] Furthermore, the function f is determined based on an empiricalformula obtained by mixing the foreign substance having differentcharacteristic quantities with respect to the size, respectively.

[0016] Thus, since the life correction coefficient a_(xyz) can beobtained based on the experimental formula obtained previously by thevalue α for the ratio, the life can be predicted at a higher accuracy.

[0017] Still further, the function f has a viscosity ratio κ of alubricant, a fatigue limit load Pu and a contamination degreecoefficient a_(c) as variables, and the contamination a_(c) has thevalue α for the ratio as a variable.

[0018] Thus, the present invention is applicable also in a case ofdetermining the correction rated life based on the life correctioncoefficient a_(xyz) using the viscosity ratio κ of the lubricant, thefatigue limit load Pu and the contamination degree coefficient a_(c) asthe variables proposed by ISO 281 in February, 2000.

[0019] A further aspect of the present invention is a life predictingdevice for a rolling bearing for conducting life prediction of a rollingbearing such that a basic dynamic rated load C and a basic static ratedload C₀ can be calculated, comprising a specification informationinputting means for inputting specification information containing abasic dynamic rated load C and a basic static rated load C₀ of therolling bearing, a dynamic equivalent load computation means forcomputing a dynamic equivalent load based on the specificationinformation inputted by the specification information inputting means, areliability setting means for setting a reliability coefficient, atypical dimension determining means for determining a typical dimensionfor a portion of a bearing in contact with mixed foreign substance, amixed foreign substance characteristic quantity inputting means forinputting a characteristic quantity showing the size of the mixedforeign substance, a ratio computing means for computing the value forthe ratio between the typical dimension and the characteristic quantity,a life correction coefficient setting means for setting a lifecorrection coefficient based on the value for the ratio, and a bearinglife computation means for computing the bearing life based on thereliability coefficient, the life correction coefficient, the basicdynamic rated load, the dynamic equivalent load and the load index.

[0020] Further, the life predicting device for a rolling bearingaccording to the present invention inputs specification information by aspecification information inputting means, sets a reliabilitycoefficient by a reliability setting means, determines a typicaldimension by a typical dimension determining means, inputting acharacteristic quantity showing the size of the mixed foreign substanceby a mixed foreign substance characteristic quantity inputting means,determining the value a for the ratio between the typical dimension andthe characteristic quantity by a ratio computing means, thereby settinga life correction coefficient a_(xyz) by computation for:

a_(xyz)∝f(α)

[0021] by a life correction coefficient setting means, and computing thebearing life L_(nm) by computation of

L _(nm) =a ₁ ×a _(xyz)×(C/P)^(p)

[0022] based on the reliability coefficient a_(xyz), the life correctioncoefficient a₁, the basic dynamic rated load C, the dynamic equivalentload P, and the load index p.

[0023] Further, a life predicting device for a rolling bearing accordingto the present invention has a feature for conducting life prediction ofa rolling bearing specified such that a basic dynamic rated load C and abasic static rated load C₀ can be calculated, comprising a specificationinformation inputting means for inputting specification informationcontaining a basic dynamic rated load C and a basic static rated load C₀of the rolling bearing, a dynamic equivalent load computation means forcomputing a dynamic equivalent load based on the specificationinformation inputted by the specification information inputting means, areliability setting means for setting a reliability coefficient, atypical dimension determining means for determining a typical dimensionfor a portion of a bearing in contact with mixed foreign substance, amixed foreign substance characteristic quantity inputting means forinputting a characteristic quantity showing the size of the mixedforeign substance, a ratio computing means for computing the value forthe ratio between the typical dimension and the characteristic quantity,a life correction coefficient setting means for setting a lifecorrection coefficient based on the value for the ratio, a bearing lifecomputation means for computing the bearing life based on thereliability coefficient, the life correction coefficient, the basicdynamic rated load, the dynamic equivalent load and the load index, anda re-computation judging means whether re-calculation is necessary ornot for matching a desired life in a case where the result ofcomputation by the bearing life computation means does not correspond tothe desired life. The bearing life predicting device for the rollingbearing judges, when the result of computation by the bearing lifecomputation means does not correspond to a desired life, whetherre-calculation is necessary or not for satisfying the desired life bythe re-computation judging means and, in a case where re-calculation isnecessary, conducts re-calculation by selecting, for example, change ofthe rolling bearing number to a greater one or change of the mixedforeign substance diameter thereby deciding a rolling bearing that cansatisfy the desired life.

[0024] The life predicting device for the rolling bearing can determinethe value a for the ratio using the contact ellipse area in the bearingand can set the life correction coefficient a_(xyz) by the value α forthe ratio.

[0025] Further, it has feature in that the life correction coefficientsetting means sets a life correction coefficient obtained bysubstituting the value for the ratio in the empirical formula obtainedby mixing the foreign substance having different characteristicquantities respectively with respect to the size in the bearing.

[0026] Since the life correction coefficient a_(xyz) can be obtainedbased on the empirical formula previously obtained by the value α forthe ratio, the life predicting device for the rolling bearing canpredict life at a higher accuracy.

[0027] Further, it has a feature in that the life correction coefficientsetting means sets the life correction coefficient with reference to aviscosity ratio of a lubricant, a fatigue limit load, and acontamination degree coefficient which changes depending on the valuefor the ratio.

[0028] The life predicting device for the rolling bearing is applicablealso in a case of determining the correction rated life based on thelife correction coefficient a_(xyz) using the viscosity ratio κ of thelubricant, the fatigue limit load Pu, and the contamination degreecoefficient a_(x) as variants proposed by ISO 281 in February, 2000.

[0029] Further, a rolling bearing selecting device using a lifepredicting device for a rolling bearing comprises a bearing speciesinputting means for inputting a bearing species desired by a user, aspecification information inputting means for inputting necessaryspecification information other than the required specificationinformation required by the user from necessary specificationinformation containing a basic dynamic rated load C and a basic staticrated load C₀ of the rolling bearing, a specification informationassuming means for comparing the required specification informationinputted by the specification information inputting means and thenecessary specification information thereby assuming the not-inputtedspecification information, a life predicting device for the rollingbearing conducting bearing life predicting computation based on thespecification information inputted by the specification informationinputting means and the specification information assumed by thespecification information assuming means, a judging means for judgingwhether the result of computation by the life predicting device cansatisfy the specification information inputted by the specificationinformation inputting means or not, a specification informationpresenting means for presenting the specification information set by thespecification information assuming means when the result of the judgmentby the judging means can satisfy the specification information, and are-computing means for changing the specification information assumed bythe specification information assuming means and conductingre-computation by the life predicting device for the rolling bearingwhen the result of the judgment of the judging means can not satisfy thespecification information.

[0030] In the rolling bearing selecting device using the life predictingdevice for the rolling bearing, a bearing type such as a ball bearing, aroller bearing, a radial bearing, a thrust bearing or the like isinputted by the bearing species inputting means and, when a user intendsto know any one of the optimal bearing, the optimal operation conditionand the life predicting time, and inputs the remaining two requireditems of specification information by the specification informationinputting means, the specification information assuming means assumedany one of the optimal bearing, the optimal operation condition and thelife predicting time, and conducts the predicting life computation basedon the required specification information and the assumed information.For example, in a case where the optimal operation condition is intendedto be known and when the name of the bearing to be used and the requiredlife time are inputted, it assumes the load exerting on the bearing, thenumber of rotations of the bearing and the mixed foreign substancediameter respectively, conducts life predicting computation, conductsthe life predicting computation while changing the specificationinformation assumed by the specification information assuming means in acase where the life predicting time does not satisfy the required lifetime and, when the life predicting computation satisfying the requiredlife time is conducted, presents the operation condition as the optimaloperation condition by the specification information presenting means.

[0031] Still further, the specification information inputting means, thespecification information assuming means, the life predicting device forthe rolling bearing, the judging means, the specification informationpresenting means and the re-computation means are adapted accessable byway of an internet.

[0032] In the rolling bearing selecting device using the life predictingdevice for the rolling bearing, any one of the optimal bearing, theoptimal operation condition, and the life predicting time can beselected easily at the information terminal owned by the user when theuser conducts access by way of the internet to the specificationinformation inputting means, the specification information assumingmeans, the life predicting device for the rolling bearing, the judgingmeans, the specification information presenting means and there-computation means.

[0033] The rolling bearing selecting device further comprises a userregistration accepting means for accepting the user registration by wayof the internet, and adapted such that only the user registered by theuser registration accepting means can access by way of the internet tothe specification information inputting means, the specificationinformation assuming means, the life predicting device for rollingbearing, the judging means, the specification information presentingmeans and the re-computation means.

[0034] In the rolling bearing selecting device using the life predictingdevice for the rolling bearing, since only the user who is registered bythe user registration accepting means can select any one of the optimalbearing, the optimal operation condition and the life predicting time byway of the internet, the user information can be obtained by the userregistration accepting means.

[0035] Since the rolling bearing selecting device using the lifepredicting device for the rolling bearing can select the language to beused in the specification information inputting means, the specificationinformation assuming means, the life predicting device for the rollingbearing, the judging means, the specification information presentingmeans and the re-computation means, the rolling bearing can be selectedby using a language desired by a user by optionally selecting a languagesuch as Japanese, English, German or French.

[0036] Further, the specification information presenting means isadapted to conduct any one of presentation for the life prediction ofthe rolling bearing, presentation of the optimal bearing andpresentation of the optimal working condition.

[0037] The rolling bearing selecting device using the life predictingdevice for the rolling bearing can appropriately present any one of thelife time, the optimal bearing and the optimal working condition of therolling bearing desired by the user.

[0038] Further it comprises a delivery information presenting meanspresenting at least one of the delivery date or the estimated sum forthe rolling bearing based on the specification information presented bythe specification information presenting means.

[0039] The rolling bearing selecting device using the life predictingdevice for the rolling bearing can present, when the specificationinformation presenting means presents the optimal bearing, the optimaloperation condition and the life predicting time, the delivery time andthe estimated sum of the corresponding bearing, so that it is notnecessary for a user to request the presentation of the delivery time orthe estimated sum.

[0040] Further, a program according to the present invention has amemory medium storing a life predicting program for predicting the lifeof a rolling bearing specified such that a basic dynamic rated load Cand a basic static rated load C₀ can be calculated, comprisingdescriptions for executing, by a computer, a step of inputtingspecification information containing the basic dynamic rated load C andthe basic static rated load C₀ of the rolling bearing, a step ofcomputing a dynamic equivalent load based on the specificationinformation, a step of setting a reliability coefficient, a step ofdetermining a typical dimension for a portion of the bearing in contactwith mixed foreign substance, a step of inputting a characteristicquantity indicating the size of the mixed foreign substance, a step ofcomputing the value for the ratio between the typical dimension and thecharacteristic quantity, a step of setting the life correctioncoefficient based-on the value for the ratio, and a step of computingthe bearing life based on the reliability coefficient, the lifecorrection coefficient, the basic dynamic rated load, the dynamicequivalent load, and the load index.

[0041] Still further, the program according to the present invention hasa memory medium storing a life predicting program for predicting life ofa rolling bearing specified such that a basic dynamic rated load C and abasic static rated load C₀ can be calculated, comprising descriptionsfor executing, by a computer, a step of inputting specificationinformation containing the basic dynamic rated load C and the basicstatic rated load C₀ of the rolling bearing, a step of computing adynamic equivalent load based on the specification information, a stepof setting a reliability coefficient, a step of determining a typicaldimension for a portion of the bearing in contact with mixed foreignsubstance, a step of inputting a characteristic quantity indicating thesize of the mixed foreign substance, a step of computing the value forthe ratio between the typical dimension and the characteristic quantity,a step of setting a life correction coefficient based on the value forthe ratio, a step of computing the bearing life based on the reliabilitycoefficient, the life correction coefficient, the basic dynamic ratedload, the dynamic equivalent load, and the load index, and a step ofjudging whether the re-computation for matching a desired life isnecessary or not in a case where the result of computation for thebearing life does not match the desired life.

[0042] A program according to the present invention has a memory mediumstoring a bearing selecting program for selecting a rolling bearing inaccordance with the specification required by a user, comprisingdescriptions for executing, by a computer, a step of inputting a bearingspecies required by a user, a step of inputting necessary specificationinformation other than the required specification information requiredby the user from the necessary specification information containing abasic dynamic rated load C and the basic static rated load C₀ of therolling bearing, a step of comparing the required specificationinformation and the necessary specification information thereby assumingthe not inputted specification information, a step of predicting life byusing the life predicting program according to claim 16 based on therequired specification information and the assumed specificationinformation other than that described above, a step of judging whetherthe result of the life prediction can satisfy the required specificationinformation or not, a step of presenting the assumed specificationinformation as the bearing selection information when the result of thelife prediction can satisfy the required specification information, anda step of changing the assumed specification information in a casewhether the result of the life prediction can not satisfy the requiredspecification information and conducting re-computation by the lifepredicting program.

[0043] The environment coefficient determining method according to theinvention determines an environment coefficient for the life correctioncoefficient used in the bearing life calculation, wherein theenvironment coefficient is determined at least by the ratio between atypical dimension for the portion of the bearing in contact with a mixedforeign substance and a characteristic quantity indicating the size ofthe mixed foreign substance.

[0044] The life correction coefficient a_(xyz) for the correction ratedlife L_(nm) proposed by ISO 281 in February, 2000 is represented as afunction by taking factors such as the fatigue limit load Pu, thelubrication state (kinetic viscosity)κ, and the environment coefficient(contamination degree of lubricant) a_(c) into consideration. Then, theweight, the size, the shape and the type of the foreign substances aretaken into consideration for the environmental coefficient(contamination degree of lubricant).

[0045] That is, according to the environmental coefficient determiningmethod, the environment coefficient (contamination degree of lubricant)a_(c) used for the bearing life calculation is quantitatively evaluatedby using at least the size of the foreign substance among the weight,size, shape and type of the foreign substances, and the evaluation isconducted by using the value α for the ratio with the typical dimensionfor the portion of the bearing in contact with the mixed foreignsubstance, without depending on the size of the bearing.

[0046] The value for the ratio is calculated by:

α=d/{square root}{square root over ( )}S

[0047] where {square root}{square root over ( )}S represents the typicaldimension assuming a typical diameter of the mixed foreign substance asd, and a contact ellipse area in the bearing as S. Thus, the value α forthe ratio is determined by using the contact ellipse area in the bearingand the environment coefficient (contamination degree of lubricant)a_(c) is determined by the determined value α for the ratio.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048]FIG. 1 is a flow chart showing an example of a life predictingmethod in a life predicting device of a first embodiment according tothe present invention;

[0049]FIG. 2 is a characteristic graph showing the result of anexperiment for determining an empirical formula for obtaining a lifecorrection coefficient a_(xyz), for the result at P/C=0.16;

[0050]FIG. 3 is a characteristic graph showing the result of anexperiment for determining an empirical formula for obtaining a lifecorrection coefficient a_(xyz), for the result at P/C=0.32;

[0051]FIG. 4 is a characteristic graph showing values by the empiricalformula;

[0052]FIG. 5 is a view showing the constitution of a life predictingdevice of a second embodiment;

[0053]FIG. 6 is a block diagram showing an electrical connectionrelation in the life predicting device of the second embodiment;

[0054]FIG. 7 is an explanatory view showing a screen for a bearingtable;

[0055]FIG. 8 is a flow chart showing an example of a life predictingmethod;

[0056]FIG. 9 is an explanatory view showing an initial menu screen;

[0057]FIG. 10 is a flow chart showing an example of a bearing selectionprocessing method;

[0058]FIG. 11 is an explanatory view for a bearing selection screen;

[0059]FIG. 12 is a flow chart showing an example of a new lifecalculation processing method;

[0060]FIG. 13 is an explanatory view showing a screen for new lifecalculation formula;

[0061]FIG. 14 is an explanatory view showing a screen for the definitionof a load coefficient;

[0062]FIG. 15 is an explanatory view showing a screen for theexplanation of a reliability coefficient;

[0063]FIG. 16 is a flow chart showing an example of a dynamic equivalentload calculation processing method;

[0064]FIG. 17 is an explanatory view showing a screen for a dynamicequivalent load;

[0065]FIG. 18 is an explanatory view showing a screen for result output;

[0066]FIG. 19 is a view showing a constitution of a bearing selectingdevice as an embodiment of the present invention;

[0067]FIG. 20 is a flow chart showing an example of a bearing selectingprocessing method executed by a WWW server;

[0068]FIG. 21 is an explanatory view showing the screen for the input ofbearing species;

[0069]FIG. 22 is an explanatory view showing a screen for the input ofspecification information;

[0070]FIG. 23 is a flow chart showing an example of an optimal operationcondition determining processing method of FIG. 20; and

[0071]FIG. 24 is a flow chart showing an example of an optimal bearingdetermining processing method of FIG. 20;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0072] Preferred embodiments of the present invention are to bedescribed with reference to the drawings.

(1) First Embodiment (First Example of a Life Predicting Device)

[0073] A life predicting device of a first embodiment is an informationprocessing device for predicting the life of a bearing, for example, bya life predicting application software and it is, for example, apersonal computer for predicting the life of a bearing by an applicationsoftware stored in a memory device. FIG. 1 shows a processing method bythe life predicting device.

[0074] At first, at step S1, data for the species of a bearing isinputted. Specifically, a basic dynamic rated load C(N), a basic staticrated load C₀(N), an inner diameter d (mm), an outer diameter D (mm) anda width B (mm) are inputted.

[0075] Then, at step S2, other data for the bearing are inputted.Specifically, bearing dimensions such as a radius of curvature ofgroove, a radius of curvature of starting surface, a number of balls, aball diameter (mm), and a clearance (mm) are inputted. Then, at step S3,a reliability coefficient a₁ is selected from the Table 1 describedabove. Then, at step S4, data for working conditions of the bearing isinputted. Specifically, a load coefficient f_(w), a radial load F_(r),an axial load F_(a), a number of rotation (min⁻¹) and a use ratio (%)are inputted.

[0076] Then, at step S5, a dynamic equivalent load P (N) and an averagenumber of rotation N (min⁻¹) are determined by properly using the datainputted in the step described above. The dynamic equivalent load isdetermined as described below.

[0077] The dynamic equivalent load P is determined according to thefollowing formula (4) based on the load coefficient f_(w), the radialload F_(r) and the axial load F_(a) inputted at the step S4 and theradial coefficient X and the axial coefficient Y set based on thespecification information:

P=X·F _(r) +Y·F _(a)  (4)

[0078] The specification table is, for example, the following Table 2.TABLE 2 $\frac{F_{a}}{F_{r}} \leqq e$

$\frac{F_{a}}{F_{r}} > e$

$\frac{f_{0}F_{a}}{Cor}$

e X Y X Y 0.172 0.19 1 0 0.56 2.30 0.345 0.22 1 0 0.56 1.99 0.689 0.26 10 0.56 1.71 1.03 0.26 1 0 0.56 1.55 1.38 0.30 1 0 0.56 1.45 2.07 0.34 10 0.56 1.31 3.45 0.38 1 0 0.56 1.15 5.17 0.42 1 0 0.56 1.04 6.89 0.44 10 0.56 1.00

[0079] According to the Table 2, since the value for f₀·F_(a)/C_(or) canbe determined if the coefficient f₀, the static rated load C_(or), andthe axial load F_(a) can be determined, the radial coefficient X and theaxial coefficient Y specified therewith are used. On the other hand, theaverage number of rotation is a number of rotation used in the lifecalculation in a case of including plural working conditions, which isan average value for the number of rotations for respective workingconditions.

[0080] The dynamic equivalent load P and the average number of rotationN are determined as described at step S5, it goes to step S6, andcalculates a basic rated life L₁₀ of the existent formula by using theformula (1) based on the determined dynamic equivalent load P and theaverage number of rotation N.

[0081] On the other hand, at step S7, it calculate a maximum rollingelement load Q_(max) according to the following formula (5) by using thedynamic equivalent load P determined at the step S4.

Q _(max) =P/number of balls  (5)

[0082] Then, at step S8, it determines a contact ellipse area S (μm²).For example, it determines the contact ellipse area S by properly usingthe data obtained in the step S8 by using the Herz's elastic contacttheory. Then, at step S9, it inputs an actually measured mixed foreignsubstance diameter d_(debris) (“debris” means “foreign substance”)(μm).

[0083] Then, at step S10, it determines the value for the ratio betweenthe contact ellipse S and the mixed foreign substance diameterd_(debris) obtained at the step S8 and the step S9 (d_(debris)/{squareroot}{square root over ( )}S, hereinafter referred to as a standardizedforeign substance diameter) and, at succeeding step S11, it determines alife correction coefficient a_(xyz) from the standardized foreignsubstance diameter (d_(debris)/{square root}{square root over ( )}S) Inthis case, the value {square root}{square root over ( )}S for the squareroot of the contact ellipse area S corresponds to a typical dimensionfor a portion of the bearing in contact with the mixed foreignsubstance, the mixed foreign substance diameter d_(debris) (μm) showsthe size of the mixed foreign substance and corresponds to acharacteristic quantity, and the standardized foreign substance diameter(d_(debris)/{square root}{square root over ( )}S) corresponds to thevalue α of the ratio.

[0084] The life correction coefficient a_(xyz) is determined based onthe standardized foreign substance diameter (d_(debris)/{squareroot}{square root over ( )}S) previously determined according to anempirical formula. The empirical formula is to be explained withreference to examples.

[0085] As test bearings, 9 numbers of 6006, 6206, 6306, 6012, 6212,6312, 6017, 6217, and 6317 by the bearing numbers shown in the followingTable 3 are used. Further, a radial load to provide P/C of 0.32 and 0.16is loaded. The square root ({square root}{square root over ( )}S) forthe contact ellipse area S calculated at the step S8 corresponding tothe bearing number and two kinds of P/C values (0.32, 0.16) takes eachvalue shown at the right end in Table 3. TABLE 3 Basic {square root over( )} dynamic contact Inner Outer rated Radial ellipse Bearing diameterdiameter Width load load area Number d (mm) D (mm) B (mm) P/C C (kgf) Fr(kgf) (μm) 6006 30 55 13 0.32 1350 432 1020 0.16 1350 216 823 6206 30 6216 0.32 1980 635 1352 0.16 1980 318 1084 6306 30 72 19 0.32 2700 8701663 0.16 2700 435 1334 6012 60 95 18 0.32 3000 960 1234 0.16 3000 480978 6212 60 110 22 0.32 5350 1712 1902 0.16 5350 856 1509 6312 60 130 310.32 8350 2672 2619 0.16 8350 1336 2078 6017 85 130 22 0.32 5050 16161572 0.16 5050 808 1248 6217 85 150 28 0.32 8550 2736 2436 0.16 85501368 1934 6317 85 180 41 0.32 13500 4320 3408 0.16 13500 2160 2704

[0086] Further, the experiment is conducted under the followingconditions as shown in the following Table 4. TABLE 4 Condition Name oftesting Ball bearing life testing machine machine (manufactured by NSKLtd.) Test load P/C = 0.16, 0.32 (2 types) Number of N = 2500 rpmrotation of bearing Test temperature 80° C. Lubricant #68 turbine oilMixed foreign Hardness HV870, HV500 (2 substance kinds) Sizes (average32 (16) μm, 74 (53) μm, foreign substance 147 (110.5) μm diameter) (3kinds) Quantity 150 ppm, 300 ppm (2 kinds)

[0087] As shown in Table 4, the mixed foreign substance is used for twohardnesses (HV 870, HV 500) for three sizes (average foreign substancediameter) of 32 (16) μm, 74 (53) μm, and 147 (110.5) μm and for twoamounts (150 ppm, and 300 ppm) in the experiment. Accordingly,experimental results under 24 conditions, (2 (kinds of P/C)×2 (kinds ofhardness of foreign substance)×3 (kinds of size of foreign substance)×2(kinds of quantity of foreign substance)) can be obtained for onebearing number.

[0088] The life test was conducted by providing the test bearings eachby the number of tens under the conditions (24 kinds of conditions foreach bearing number). The test was interrupted when the vibration valuefor the test bearing on a testing machine reached twice the initialvibration value, and the life was judged by confirming the presence orabsence of flaking at the raceway groove surface, and the time theflaking was confirmed was defined as the life.

[0089] The test life is defined up to five times of the calculated lifeof 52%-52% use as groove R specified according to JIS (hereinafterreferred to as L_(cal)) at the longest and the test is terminated whenthe longest time is reached. 52% mentioned herein is a groove todiameter ratio of outer and inner rings (r_(e)/D_(a), r_(i)/D_(a))assuming the diameter of a rolling element as D_(a) and the groovediameters of the outer ring and the inner rings as r_(e) and r_(i).

[0090] The actually measured life L_(exp), was determined from a totalrotation time till occurrence of flaking in 10% of 10 test specimensfrom the side of the shorter life according to the Weibull distributionfunction (that is, 10% life), and the value was used.

[0091]FIG. 2 and FIG. 3 are examples for the result of the life test. Ineach of the graphs, the abscissa expresses the standardized foreignsubstance diameter (d_(debris)/{square root}{square root over ( )}S) andthe ordinate expresses the life correction coefficient a_(xyz). Thevalue for the life correction coefficient a_(xyz) on the ordinate is avalue obtained as a ratio between the actually measured life L_(exp) andthe calculation life L_(cal) (L_(exp)/L_(cal)) according to the relationof formula (2) assuming the reliability coefficient a₁ as 1.

[0092]FIG. 2 shows the result of the life test for the test bearings for9 kinds of bearing numbers (6006, 6206, 6306, 6012, 6212, 6312, 6017,6217 and 6317) under the conditions at a test load: P/C=0.16, with ahardness of mixed foreign substance of HV 870 and HV 500, the size offoreign substance of 32 (16) μm, 74 (53) μm, and 147 (110.5) μm and thequantity of foreign substance of 150 ppm. The basic rated fatigue lifeunder the conditions is: L₁₀=1356.3 (hr).

[0093] Further, FIG. 3 shows the result of the life test on the testbearings for 9 kinds of bearing numbers described above under theconditions at a test load: P/C=0.32, with the hardness of mixed foreignsubstance of HV 870 and HV 500, the size of foreign substance of 32 (16)μm, 74 (53) μm, and 147 (110.5) μm and the quantity of foreign substanceof 150 ppm. The basic rated fatigue life under the conditions is:L₁₀=169.5 (hr).

[0094] As shown in FIG. 2 and FIG. 3, it can be confirmed that the lifecorrection coefficient a_(xyz) decreases in the manner of an exponentialfunction as the standardized foreign substance diameter(d_(debris)/{square root}{square root over ( )}S) increases. Accordingto plural experimental points described above, approximate formulae (6)and (7) can be obtained for each of the conditions: P/C=0.16, and 0.32as shown in FIG. 4.

y=1.0748e ^(−43.449x)  (6)

y=0.3914e ^(−52.427x)  (7)

[0095] In the formula (6) and formula (7), x corresponds to thestandardized foreign substance diameter (d_(debris)/{square root}{squareroot over ( )}S), and y corresponds to the life correction coefficienta_(xyz)). The empirical formula of the following formula (8) is obtainedfrom the formula (6) and the formula (7).

a _(xyz)=0.394{(u/0.16)−1}·e ^(−52,427t)+1.0748{2−(u/0.16)}·e^(−43.449)  (8)

[0096] in which u is a value for the load P/C exerting on the bearingand t is the value d_(debris)/{square root}{square root over ( )}Sdescribed above.

[0097] The correction coefficient a_(xyz) is obtained by substitutingthe value t (d_(debris)/{square root}{square root over ( )}S) and thevalue e (P/C) as the working conditions in the formula (8) as theempirical formula showing the relation between the standardized foreignsubstance diameter (d_(debris)/{square root}{square root over ( )}S) andthe life correction coefficient a_(xyz).

[0098] In the empirical formula, the test load is determined only forthe conditions at P/C=0.16 and 0.32, because they are upper and lowerlimit values of the test load applied usually.

[0099] By using the empirical formula described above, the lifecorrection coefficient a_(xyz) is determined from the standardizedforeign substance diameter (d_(debris)/{square root}{square root over ()}S) at step S11.

[0100] At the succeeding step S12, a final life L_(obs) (correctionrated life L_(nm)) is determined by using the basic rated life L₁₀determined at the step S6.

[0101] As described above, the correction rated life L_(nm) as the lifeprediction value can be obtained by the life predicting device.

[0102] According to the life predicting device described above, a usercan calculate the correction rated life L_(nm) by inputting the bearingtype such as the basic dynamic rated load C (N), the basic static ratedload C₀(N), the inner diameter d (mm), the outer diameter D (mm), andthe width B (mm) (step S1), inputting the bearing dimension such as theradius of curvature of groove, radius of curvature of starting surface,the number of balls, the ball diameter (mm), and the clearance (mm),inputting the reliability coefficient (a₁) selected with reference toTable 1 (step S3), inputting the data for the bearing working conditionssuch as the load coefficient (f_(w)), the radial load F_(r), the axialload F_(a), the number of rotation (min⁻¹) and the use ratio (%) thestep S4 and then inputting the actually measured mixed foreign substancediameter d_(debris) measured, for example, by a particle measuringinstrument (step S9), by using the life predicting device based on theinputted data described above.

[0103] Then, in the life predicting device, since the life correctioncoefficient a_(xyz) is determined by the empirical formula used in thestep S11 described above while taking the characteristic quantityshowing the size of the foreign substance into consideration, the lifeprediction obtained based on the life correction coefficient a_(xyz) isdetermined properly while reflecting the characteristic of the mixedforeign substance.

[0104] Accordingly, since the quantitative evaluation is made whileconsidering the size and the shape of the mixed foreign substance by thelife correction coefficient a_(xyz), the life predicting device canprovide the bearing life obtained according to the formula (2) above aspredicted at a high accuracy.

[0105] In the processings described above, the processings at the stepS1, the step S2, and the step S4 correspond to the specificationinformation inputting means, the processing at the step S3 correspondsto the reliability setting means, the processing at the step S5corresponds to the dynamic equivalent load computation means, theprocessings at the step S7 and the step S8 correspond to the typicaldimension determining means, the processing at the step S9 correspondsto the mixed foreign substance characteristic quantity inputting means,the step S10 corresponds to the ratio computation means, the processingat the step S11 corresponds to the life correction coefficient settingmeans, and the processings at the step S6 and the step S12 correspond tothe bearing life computation means.

(2) Second Embodiment (Second Example of a Life Predicting Device)

[0106] Then, a life predicting device of a second embodiment is to bedescribed.

[0107] A life predicting device of the second embodiment is, as shown inFIG. 5, a personal computer 1 comprising a computer main body 2, adisplay 3 which is a liquid crystal display or a CRT connectedtherewith, a key board 4, a mouse 5 and a printer 6 connected with thecomputer main body 2.

[0108] The internal circuit of the computer main body 2, as shown inFIG. 6, comprises a central processing unit 11, a memory device 13 suchas ROM and RAM connected to the central processing unit 11 by way of asystem bus 12, a display controller 14 for connecting the display 3 tothe system bus 12, a key board interface 15 for connecting the key board4 to the system bus 12, a mouse interface 16 for connecting the mouse 5to the system bus 12, an input/output interface 17 for connecting theprinter 6 to the system bus 12, and a hard disk 19 connected by way of ahard disk controller 18 to the system bus 12.

[0109] In this case, an operating system is accommodated in the harddisk 19, and a life predicting application software for predicting thelife of a rolling bearing and an electronic catalog storing thespecification information of rolling bearings are also accommodated.

[0110] Further, as shown in FIG. 7, the electronic catalog storesspecification information such as bearing species, bearing number, maindimension, and basic dynamic rated load C. The electronic catalog mayalso further store information such as a basic static rated load C₀, acoefficient f₀, an allowable number of rotation, a radial coefficient Xand an axial coefficient Y. In this case, the basic static loadcoefficient C₀, the coefficient f₀, the allowable number of rotation,the radial coefficient X and the axial coefficient Y can be seen byscrolling the screen by the manipulation to the mouse 5 and the like.

[0111] Further, the life predicting application software executespredetermined computation based on the input specification informationby utilizing the table calculation application software to conduct lifepredicting processing of a rolling bearing.

[0112] In the life predicting processing, as shown in FIG. 8, an initialmenu screen is displayed at first at step S21.

[0113] The initial menu screen displays, as shown in FIG. 9, functionsstored in the application software selectably, which displays a bearingchoice selection area A1, a new life calculation formula selection areaA2, a bearing life calculation formula (existent formula) selection areaA3, a product introduction selection area A4, and an end button 21.

[0114] Then, it goes to step S22, and judges whether the bearing choiceselection area A1 is selected or not by the mouse 5 or the key board 4.In a case it is selected, it goes to step S22 a, executes the bearingselection processing to be described later and then ends the processing.In a case the bearing choice selection area A1 is not selected, it goesto step S23.

[0115] At step S23, it judges whether the new life calculation formulaselection area A2 is selected or not and, if it is selected, it goes tostep S23 a, executes a new life calculation processing described laterand then ends the processing. If the new life calculation formulaselection area A2 is not selected, it goes to step S24.

[0116] At step S24, it judges whether the bearing life calculationformula (existent formula) selection area A3 is selected or not by themouse 5 or the key board. In a case where it is selected, it goes tostep S24 a, calculates the bearing life L₁₀ by the existent formula inaccordance with the formula (1) described above and then ends theprocessing. If the bearing life calculation formula (existent formula)selection area A3 is not selected, it goes to step S25.

[0117] At step S25, it judges whether the product introduction selectionarea A4 is selected or not by the mouse 5 or the keyboard 4. If it isselected, it goes to step S25 a, executes the product introductionprocessing of displaying the product introduction information previouslystored in the hard disk 19 on the display 3 and then ends theprocessing. If the product introduction selection area A4 is notselected, it goes to step S26.

[0118] At step S26, it judges whether the end button 21 is selected ornot by the mouse 5 or the key board 4 or not and, if the end button 21is selected, it ends the life predicting processing as it is. If the endbutton 21 is not selected, it returns to the step S22.

[0119] In the bearing selection processing at step S22 a, as shown inFIG. 10, it at first displays at step S31 a bearing selection screenshown in FIG. 11 on the display 3.

[0120] The selection screen displays, as shown in FIG. 11 displays aretrieve area 22 retrieving from a bearing table, a retrieve area 23retrieving from the bearing number, a menu button 24 for displaying theinputted specification information of the rolling bearing and an endbutton 24. The retrieve area 22 displays text input areas 22 a to 22 cfor inputting minimum values and maximum values of the inner diameter d,the outer diameter D, and the width (height) B (T), a deep groove ballbearing selection button 22 d, an angular ball bearing selection button22 e, s self-aligning ball bearing selection button 22 f, a singledirection thrust ball bearing selection button 22 g, a cylindricalroller bearing selection button 22 h, a tapered roller bearing selectionbutton 22 i, a self-aligning roller bearing selection button 22 j and athrust roller bearing selection button 22 k for selecting bearingspecies. Further, the retrieve area 23 displays a text input box 23 afor inputting the bearing number and a reference button 23 b displayinga list of bearing numbers.

[0121] Then, it goes to step S32 and judges whether the input for theinner diameter d, the outer diameter D, and the width (height) B (T) hasbeen completed and selection for the bearing type has been ended or notin the case of retrieving from the bearing table, or whether the inputof the bearing number has been ended or not in the case of retrievingfrom the bearing number and waits for the end of the input if one ofthem has not yet been ended till the end of the input. If the input hasbeen ended, it goes to step S33 and judges whether this is the retrievalfrom the bearing table or not and, if it is retrieved from the bearingtable, it goes to step S34, retrieves the electronic catalog based onthe inner diameter d, the outer diameter D, the width (height) B (T),and the bearing species, displays the bearing table screen shown in FIG.7 for displaying the corresponding specification information and thengoes to step S36. If retrieval is selected from the bearing number, itgoes to step S35, retrieves the electronic catalog based on the bearingnumber inputted to the text input box 23 a, displays the bearing tablescrew shown in FIG. 7 for displaying the corresponding specificationinformation and then goes to step S36.

[0122] In this case, the bearing table screen displays, as shown in FIG.7, a specification information display area 31 for displaying thecorresponding specification information of the electronic catalog, anexistent formula life calculate button 32, a new life calculate button33 according to the invention, a return button 33, a menu button 36, andan end button 37.

[0123] At step S36, it selects a desired bearing number and then judgeswhether the existent formula life calculate button 32 is selected or notand, if the existent life calculate button 32 is selected, it goes tostep S36 a, conducts computation of the formula (1) to execute theexistent formula life calculation processing of calculating the basicrated life L₁₀ and then ends the processing. In a case if the existentlife calculate button 32 is not selected, it goes to step S37.

[0124] At step S37, it selects a desired bearing number, then judgeswhether the new life calculate button 33 is selected or not and, if thenew life calculate button 33 is selected, it goes to step S 37 b,conducts new life calculation processing to be described later and endsthe processing. In a case if the new life calculate button 33 is notselected, it goes to step S38.

[0125] At step S38, it judges whether the menu button 36 is selected ornot and, if the menu button 36 is selected, it goes to step S38 a,actuates the initial menu display processing shown in FIG. 8 and thenends the processing. In a case if the menu button 36 is not selected, itgoes to step S39.

[0126] At step S39, it judges whether the end button 37 is selected ornot and, if the button is selected, it ends the life calculationprocessing as it is. In a case if the end button 37 is not selected, itgoes to step S40 and judges whether the return button 35 is selected ornot and, if the button is selected, it returns to the step S31. In acase if the return button 35 is not selected, it returns to the stepS36.

[0127] In the new life calculation processing at the steps S23 a and S37a, it at first displays at step S51, as shown in FIG. 12, displays a newlife calculation screen shown in FIG. 13.

[0128] Further, the new life calculation screen has a display area 41for displaying predetermined items, and a calculation execute button 42,a read button 43, a preserve button 44, an initialize button 45, areturn button 46 and a menu button 47 arranged below the display area41.

[0129] In this case, the display area 41 displays the life calculationformula of the formula (2) in a heading portion, and has a combo box 51for selecting the bearing type, a text box 52 for inputting the bearingnumber, a text box 53 for inputting a bearing dynamic rated load C, atext box 54 for inputting a bearing static rated load C₀, a text box 55for inputting a bearing inner diameter d, a text box 56 for inputting abearing outer diameter D, a text box 57 for displaying a bearing dynamicequivalent load P, a text box 57 for inputting a load coefficient f_(w),a combo box 59 for selecting a reliability coefficient a₁, a dynamicequivalent load calculate button 60 for indicating the calculation ofthe dynamic equivalent load, a text box 60 for inputting the radius ofcurvature of groove, a text box 61 for inputting the radius of curvatureof raceway surface, a text box 62 for inputting the number of balls, thetext box 63 for inputting the ball diameter, a text box 64 for inputtingthe clearance, a text box 65 for inputting the mixed foreign substancediameter, a dynamic equivalent load calculate button 66, a combo box 67for selecting the specification of the bearing material, and a selectbutton 68 for selecting the absence or presence of a particular inputfor the fatigue limit load Pu. Then, the text box 58 for the loadcoefficient f_(w) displays “1.0”, the combo box 59 for the reliabilitycoefficient a₁ displays “90”, and the combo box 67 for the specificationof the bearing material displays “high carbon chromium bearing steel(SUJ2Z, SUJ3Z)” as default values.

[0130] Then, it goes to step S52 and judges whether the read button 43is selected or not and directly goes to step S58 if the button is notselected. In a case where the read button 43 is selected, it goes tostep S58 and successively displays the specification information for therolling bearing of the bearing number selected in the bearing table ofFIG. 7 in the order of the combo box 51 and the text box 52. When itdisplays the bearing outer diameter D in the text box 56, it goes tostep S54 and displays the screen for the definition of the loadcoefficient having a display area 61 for displaying the description forthe definition of the load constant and a close button 62 shown in FIG.14. Then, it goes to step S55, and judges whether the close button 62 isselected or not and, if the button is not selected, it waits till theselection and goes to step S56 when it is selected.

[0131] Then, at step S56, it displays a screen for the explanation ofthe reliability coefficient having a display area 63 for displaying asentence for the reliability coefficient and a close button 64 shown inFIG. 15, then goes to step S57 and judges whether the close button 64 isselected or not. In a case if the button is not selected, it waits tillselection and, if the close button 64 is selected, it goes to step S58.

[0132] At step S58, it judges whether the dynamic equivalent loadcalculate button 66 is selected or not and, if it is selected, it goesto step S59, conducts the dynamic equivalent load calculation describedlater and then goes to step S60. In a case if the dynamic equivalentload calculate button 66 is not selected, it goes to step S60 as it is.

[0133] At step S60, it judges whether the calculate execute button 42 isselected or not and, if the calculate execute button 42 is selected, itgoes to step S61 and judges whether the data necessary for calculationhas already been inputted or not. The data necessary for the calculationis the data to be inputted to the text box displayed in the display area41 described above, which is the data necessary for determining thecorrection rated life L_(nm).

[0134] If not all the data necessary for the calculation are inputted,it goes to step S62, displays message information for promoting thecompletion of the input of the data necessary for the calculation andthen returns to the step S61 and stays in a data input waiting state. Onthe other hand, when all the data necessary for the calculation havebeen inputted, it goes to step S63.

[0135] At step S63, it judges whether the calculation for the dynamicequivalent load P is ended or not and, if it is not ended, it goes tostep S64, displays message information for promoting the precedentcompletion for the calculation of the dynamic equivalent load Pprecedingly, and then returns to the step S58. If the calculation forthe dynamic equivalent load P is completed, it goes to step S65 andcomputes the formula (2) to conduct life calculation processing forcalculating the correction rated life L_(nm).

[0136] That is, it determines the maximum rolling element load Q_(max)based on the formula (5) from the dynamic equivalent P determined at thestep S59 (processing at step S7 shown in FIG. 1) and successivelydetermines the contact ellipse area S (μm²) (processing at step S8 shownin FIG. 1). Then, it calculates the standardized foreign substancediameter (d_(debris)/{square root}{square root over ( )}S) based on thecontact ellipse area S (μm²) and the mixed foreign substance diameter(d_(debris)) inputted to the text box 65, and calculates the lifecorrection coefficient a_(xyz) based on the formula (8) as thepreviously obtained empirical formula (8). On the other hand, itcalculates the basic rated life L₁₀ based on the formula (1) from thedynamic equivalent load P. Then, it calculates the correction rated lifeL_(nm) according to the formula (2) based on the calculated lifecorrection coefficient a_(xyz) and the basic rated life L₁₀.

[0137] After conducting the life calculation processing of calculatingthe correction rated life L_(nm), it ends the processing and goes tostep S60 in a case if the result of judgment at the step S60 showingthat the calculation execute button 42 is not selected, it goes to stepS66 and judges whether the preserve button 44 is selected or not. In acase if the preserve button 44 is selected, it goes to step S67 andpreserves data displayed on each boxes 51 to 65 at that instance andthen returns to the step S60. In a case if the preserve button 40 is notselected, it goes to step S68.

[0138] At step S68, it judges whether the initialize button 45 isselected or not and, if the initialize button 45 is selected, it goes toS69, deletes the displayed data and then returns to the step S52. In acase if the initialize button 45 is not selected, it goes to step S70and judges whether the return button 46 is selected or not. In a case ifthe return button 46 is selected, it returns to step S33 in the bearingselection processing in FIG. 10. In a case where the return button 46 isnot selected, it goes to step S71 and judges where the menu button 40 isselected or not. In a case if the menu button 47 is selected, it goes tostep S72, starts the initial menu display processing and ends theprocessing. In a case if the menu button 47 is not selected, it returnsto the step S58.

[0139] The dynamic equivalent load calculation processing executed atthe step S59 by the selection of the dynamic equivalent calculate button66 at the step 58 displays, specifically, as shown in FIG. 16, a dynamicequivalent load calculation screen shown in FIG. 17 at first at stepS81.

[0140] The dynamic equivalent load calculation screen has a display area71 for indicating predetermined items and a calculation execute button72, a result reflect button 73, a return button 74 and a menu button 75displayed below the display area 71.

[0141] The display area 71 has a combo box 76 for selectively displayingthe bearing type, a text box 77 for displaying the bearing number, atext box 78 for inputting the radial load f_(r) of working condition, atext box 79 for inputting an axial load f_(a), a text box 80 forinputting the number of rotation, a text box 81 for inputting the usecondition ratio, an additional input button 82, a text box 83 fordisplaying the dynamic equivalent load P and a text box 84 displayingthe average number of rotation N.

[0142] Then, it goes to step S82, judges whether the calculation executebutton 72 is selected or not and, in a case if the calculation executebutton 72 is selected, it goes to step S83, calculates the dynamicequivalent P by computing the formula (4) based on the radial load F_(r)and the axial load F_(a) inputted to the text boxes 78 and 79, theradial coefficient X and the axial coefficient Y set by thespecification information, and the load coefficient f_(w) set on the newlife calculation screen in FIG. 13, displays the calculated dynamicequivalent load P on the text box 83 and then goes to step S84.

[0143] At step S84, it judges whether the result reflect button 73 isselected or not and, in a case if the result reflect button 73 isselected, it goes to step S85, reflects the calculated dynamicequivalent load P in the text box 57 for the dynamic equivalent load inthe new life calculation formula screen in FIG. 13, then goes to stepS86, closes the dynamic equivalent load calculation screen in FIG. 17,actuating the new life calculation screen in FIG. 13 and then ends theprocessing.

[0144] Further, in a case if the calculation execute button 72 isselected at step S82, and if the result reflect button 73 is notselected at the step S84, it goes to step S87 and judges whether thereturn button 74 is selected or not. In a case if the return button 70is selected, it goes to step S86, re-displays the new life calculationscreen of FIG. 13 and ends the processing. In a case if the returnbutton 74 is not selected, it goes to step S88 and judges whether themenu button 75 is selected or not. In a case if the menu button 75 isselected, it goes to step S89, activates the initial menu displayprocessing the FIG. 8 and then ends the processing. In a case if themenu button 75 is not selected, it returns to the step S82.

[0145] The result of various calculations determined at the step S65 aredisplayed as the result output screen shown in FIG. 18.

[0146] The result output screen has a display area 91 for displayingpredetermined items, and a print button 92, a return button 93 and menubutton 94 arranged below the display area 91. The display area 91comprises a text box 95 for displaying a bearing type, a text box 96 fordisplaying the bearing number, a text box 97 for displaying the bearingdynamic rated load, a text box 98 for displaying the bearing staticrated load, a text box 99 for displaying the bearing dynamic equivalentload, a text box 100 for displaying the number of rotation, a text box101 for displaying the contact ellipse area S, a text box 102 fordisplaying the standardized foreign substance diameter(d_(debris)/{square root}{square root over ( )}S), a text box 103 fordisplaying the reliability coefficient a₁, a text box 104 for displayinga life correction coefficient a_(xyz), a text box 105 for displaying thebasic rated life L₁₀ and a text box 106 for displaying the correctionrated life L_(nm) of the rolling bearing.

[0147] The shows processings attained by the life predicting device ofthe second embodiment. The following processings are conducted by auser's operations.

[0148] Now assuming that the life of a deep groove ball bearing having,for example, a bearing number of “6206” is to be predicted. At first, apower source for the computer main body is turned on to actuate theoperating system and then the life predicting application software isstarted.

[0149] Thus, execution for the life predicting processing for therolling bearing shown in FIG. 8 is started, and the initial menu screenshown in FIG. 9 is at first displayed. In the initial menu screen, whenthe selection area A₁ for the choice of bearing is clicked, for example,by the mouse 5, the screen for the selection of the bearing shown inFIG. 11 is displayed. In a case where the bearing is retrieved from thebearing table, at least each of the text boxes 22 a, 22 b, and 22 c forthe inner diameter, the outer diameter and the width are selectedsuccessively by the mouse 5, the desired dimensions “30”, “62”, and “16”each by the milli unit are inputted from the key board 4, and the deepgroove ball bearing select button 22 d is selected.

[0150] Thus, the electronic catalog is retrieved and the specificationinformation such as main dimensions d, D, B, r, and basic dynamic ratedload C (also including the basic static rated load C₀, the coefficientf₀, the allowable number of rotation, the radial coefficient X, and theaxial coefficient Y although not illustrated) for the correspondingbearing number “6206” are displayed in outlined characters on thebearing table screen in FIG. 7. Further, also in a case of directlyinputting the bearing number “6202”, the bearing table screen of FIG. 7is also displayed.

[0151] In the bearing table screen, when the new calculate button 33 isselected by clicking the mouse 5, the new life calculation formulascreen of FIG. 13 is displayed and, when the read button 43 is clickedon the new life calculation formula screen, specification informationfor the bearing number selected in the bearing table of FIG. 7 areinputted successively. That is, “deep groove ball bearing” is displayedas the bearing type in the combo box 51, “6202” is displayed in the textbox 52 for bearing number, “1980” is displayed in the text box 53 forbearing dynamic rated load C, “30” is displayed in the text box 55 forthe bearing inner diameter d, and “62” is displayed in the text box 56for the bearing outer diameter D.

[0152] Then, the definition screen for the load constant shown in FIG.14 is displayed above the new life calculation screen, and the loadcoefficient f_(w) is determined from the operation condition or theplace for use with reference to the definition screen. In this example,the load coefficient f_(w) is defined to “1.0” as a default value so asto be used for example in electromotive machines, machine tools or airconditioning machines in a smooth operation with no impact shocks.

[0153] Then, when the close button 62 is selected, the definition screenfor the load coefficient is closed and, instead, the explanatory screenfor the reliability coefficient shown in FIG. 15 is displayed, and thereliability coefficient a₁ is determined with reference to theexplanatory screen for the reliability coefficient. In this example,“100” is determined as the reliability coefficient a₁ by determining thereliability to 90% as the default value.

[0154] Then, when the close button 64 is selected by the mouse 5, theexplanatory screen for the reliability coefficient is closed to actuatethe new life calculation screen. In this case, necessary informationsuch as determined load coefficient f_(w), reliability coefficient a₁,radius of curvature for groove, radius of curvature for raceway surface,number of balls, ball diameter, clearance, and mixed foreign substancediameter are inputted to the text box 58 to text box 64 respectively byusing the key board 4. Since the default values are used for the valuesof the load coefficient f₂, and the reliability coefficient a₁ in thisexample, inputting is saved.

[0155] In this state, when the dynamic equivalent load calculate button66 is selected by the mouse 5, the dynamic equivalent 6 calculationscrew shown in FIG. 17 is displayed. In the dynamic equivalent loadcalculation screen, the theoretical radial load F_(r) and thetheoretical axial load F_(a) determined from the working conditions areinputted into the text boxes 78 and 79 by using the key board 4, as wellas the number of rotation, for example, “5000” min⁻¹ is inputted intothe text box 80 by using the key board 4. In this case, if pluralworking conditions are present, the additional input button 82 isselected by the mouse 5 and then the theoretical radial load F_(r),theoretical axial load F_(a), the number of rotation N and the workingcondition ratio are inputted by using the key board 4.

[0156] In the state where the inputs have been completed, thecomputation for the formula (4) is conducted by selecting thecalculation execute button 72 by the mouse 5 to calculate the dynamicequivalent load P, and the average number of rotation N is calculated ina case where the plural working conditions are present, and the numberof rotation inputted to the text box 80 is calculated as the number ofrotation N in a case of single condition, and the calculated dynamicequivalent load P and the average number of rotation N are displayed inthe text boxes 83 and 84.

[0157] Then, when the reflect button 73 is selected by the mouse 5, thedynamic equivalent load calculation screen is closed and the new lifecalculation formula screen of FIG. 13 is actuated to display thecalculated dynamic equivalent load P and the average number of rotationN in the text boxes 57 and 61. Further, for example, in a case where thecalculated dynamic equivalent load P exceeds 50% of the basic dynamicrated load C or exceeding the basic static rated load C_(O), a warningmessage is displayed.

[0158] Then, when the calculation execute button 42 is selected by themouse 5, the maximum rolling element load Q_(max), and the contactellipse area S are calculated based on the inputted data, further, thestandardized foreign substance diameter (d_(debris)/{square root}{squareroot over ( )}S) is calculated from the calculated contact ellipse areaS and the inputted mixed foreign substance diameter d_(debris), and thelife correction coefficient a_(xyz) is calculated based on the empiricalformula (8) based on the calculated standardized foreign substancediameter (d_(debris)/{square root}{square root over ( )}S), the formula(2) is calculated based on the life correction coefficient a_(xyz) andthe calculated dynamic equivalent load P, and the result output screwshown in FIG. 18 is displayed, to display the contact ellipse area S,the standardized foreign substance diameter (d_(debris)/{squareroot}{square root over ( )}S), the reliability coefficient a₁, the lifecorrection coefficient a_(xyz), the basic rated life L₁₀ and thecorrection rated life L_(nm) into the text box 141 to text box 146.

[0159] When the print button 92 is selected by the mouse 5 and clickedon the result output screen, all the data displayed on the result outputscreen are printed by the printer 6.

[0160] Then, it is judged as to whether the calculated bearing life cansatisfy the bearing life desired by a user or not and the processing isended if it is satisfied. However, if the bearing life desired by theuser is not satisfied, the bearing number is changed to make the size ofthe bearing to be used larger, or the foreign substance mixed diameteris changed or the like and the correction rated life L_(nm) iscalculated again based thereon to select the rolling bearing that cansatisfy the bearing life desired by the user.

(3) Third Embodiment (Rolling bearing selecting device using the lifepredicting device)

[0161] Then, a rolling bearing selecting device using the lifepredicting device of a third embodiment according to the presentinvention is to be described.

[0162] The rolling bearing selecting device is, as shown in FIG. 19,applied to a WWW (World Wide Web) server 202, which is connected to aninternet 200 by way of a router 201, in which an electronic catalog forstoring a bearing selection application software including a lifepredicting application software and specification information forrolling bearings are stored in the hard disk thereof.

[0163] The bearing selection application software executes the rollingbearing selection processing including the life predicting processingfor rolling bearings in the life predicting device of the secondembodiment described above based on the inputted specificationinformation utilizing the table calculation application software or thelike to present optimal bearing, optical operation condition and lifepredicting time desired by a user.

[0164] In the rolling bearing selecting processing, as shown in FIG. 20,it at first judges at step S401 whether there is an access from ainformation processing apparatus such as a personal computer of a userby way of the internet 200 and, in a case if there is no access from theuser, it stands-by till the access arrives. In a case where the accessarrives from the user, it goes to step S402 and sends a displayinformation for the displaying the bearing the selection screen having alanguage selection section for selecting Japanese, English, German,French, etc. as the language, then goes to step S403, judges whatlanguage is selected, executes the notation processing for the selectedlanguage and then goes to step S404.

[0165] At the step S404, it requests for the input of the user's accountinformation and password, sends an input screen information forpromoting the user registration to a user's information processingapparatus in a case where the user is not registered and then goes tostep S405 and judges whether the input of the user's account informationand the password has been conducted or not. In a case if the input forthem has been conducted, it goes to step S409 to be described later andin a case where the input for the user's account information and thepassword is not conducted, it goes to step S406, judges whether the userregistration has been selected or not and if it is not selected, it goesto the step S407, judges whether the user's access is ended or not andreturns to the step S401 in a case where the user's access is ended. Ina case where the user access is not ended, it returns to the step S405.

[0166] Further, as the result of judgment at the step S406, if the userregistration is selected, it goes to step S408, executes userregistration processing and then goes to step S409. In the userregistration processing, it sends an input screen information fordisplaying the input screen that inputs full name, company name,division name, electronic mail address or telephone number to the usersinformation processing apparatus and, when predetermined items have beeninputted to the input screen information, issues the user's accountinformation and password, ends the processing and goes to the step S409.

[0167] At the step S409, it sends purchase information input screeninformation for inputting the desired bearing delivery date and desiredbearing cost to the user's information processing apparatus, then goesto step 410, and judges whether the desired delivery date and thedesired cost of the bearing have been inputted or not based on thepurchase information input screen information. When one or both of themhas been inputted, it goes to step S411, stores the inputted desiredbearing delivery date and/or desired cost to a predetermined memory areaand then goes to step S413. In a case if the bearing desired deliverydate and the delivery cost are not inputted, it goes to step S412 andjudges whether a skip button is selected or not. In a case if the stepbutton is not selected, it returns to the step 410 and in a case if theskip button is selected, it goes to step S413.

[0168] At step S413, it sends a display information for displaying thebearing species display screen shown in FIG. 21 for inputting thebearing species to the user's information processing apparatus. Thebearing species display screen displays a check box 211 for selectingwhether the bearing is a ball bearing or the roller bearing, a check box212 for selecting whether the bearing is a radial bearing or a thrustbearing, a check box 213 for selecting the presence or absence of thedesignation for the row, a dropdown box 214 for selecting single row,double row and plural row, a return button 215 and a next button 216, inwhich the check boxes 211 and 212 are set as essential input items.

[0169] Then, it goes to step S414 and judges whether the next button 216is selected or not. In a case if the button is not selected, it goes tostep S415 and judges whether the return button 215 is selected or not.In a case if the button is not selected, it returns to the step S414and, if the button is selected, it returns to the step S409.

[0170] Further, as the result of judgment at the step S414, in a casewhere the next button 216 is selected, it goes to step S416, and sendsthe display information for displaying the specification informationinput screen shown in FIG. 22 to the user's information processingapparatus. The specification information input screen has a display area221 for displaying predetermined items, a calculation execute button222, a read button 223, a preserve button 224, an initialize button 225and a return button 226 arranged below the display area 221.

[0171] In this case, the display area 221 comprises a combo box 231 forselecting the bearing type, a text box 232 for inputting the bearingnumber, a text box 233 for inputting the bearing dynamic rated load C, atext box 234 for inputting the bearing static rated load C₀, a text box235 for inputting the bearing inner diameter d, a text box 236 forinputting the bearing outer diameter D, a text box 237 for displayingload P/C exerting on the bearing, a text box 238 for inputting thenumber of rotation, a text box 239 for inputting the mixed foreignsubstance diameter, a text box 240 for inputting the required bearinglife time L_(D) and a combo box 241 for selecting the specification ofthe bearing material. Then, “high carbon chromium bearing steel (SUJ2Z,SUJ3Z)” is displayed as the default value in the combo box 241 for thespecification of the bearing material. Further, by selecting the readbutton 223 in a state of inputting the bearing number into the text box232, the bearing dynamic rated load C, the bearing static rate load C₀,the bearing inner diameter, and the bearing outer diameter correspondingto the bearing number are displayed respectively in the text boxes 233to 236. By selecting the preserve button 224, each of the data stored inthe display area 221 is preserved and, when the initialized button 225is selected, the data in the display region 221 return to the initialstate.

[0172] Then, it goes to step S417 and judges whether the calculationexecute button 222 is selected or not and in a case if the calculationexecuted button is not selected, it goes to step S418 and judges whetherthe return button 226 is selected or not. In a case if the return button226 is selected, it goes to the step S413 and, in a case if the returnbutton 226 is not selected, it returns to the step 417.

[0173] Further, in a case where the calculation execute button 222 isselected as a result of judgment at the step S317, it goes to step S419and judges whether the bearing number is inputted or not. In a casewhere the bearing number is inputted, it goes to step S420 and judgeswhether the operation condition items of the load P/C exerting on thebearing, the number of rotation of the bearing, the mixed foreignsubstance diameter and the specification for the bearing material areinputted or not. In a case if the operation condition items areinputted, it judges that the user requests for the bearing life time andgoes to step S422 and calculates the dynamic equivalent load P, themaximum rolling element load Q_(max), the contact ellipse area S (μm²),the standardized foreign substance diameter (d_(debris)/{squareroot}{square root over ( )}S), and the life correction coefficienta_(xyz) in the same manner as the processing conducted by the lifepredicting device of the first embodiment described above and calculatesthe correction rated life L_(nm) based thereon. For the values necessaryin the course till the correction rated life L_(nm) is obtained andwhich are not requested for the user to input, general default valuesare used for instance.

[0174] It calculates the correction rated life L_(nm) and then goes tostep S423 to display the correction rated life L_(nm), and sends thedisplay screen information for displaying the optimal delivery date anddelivery cost of the bearing to the user's information processingapparatus and then goes to step S424, and judges whether the end buttonincluded in the display screen information is selected or not. In a caseif the end button is selected, it returns to the step S401 and in a caseif the end button is not selected, it goes to step S425 and judgeswhether the return button is selected or not. In a case if the returnbutton is selected, it returns to the step S416 and, in a case if thereturn button is not selected, it returns to step S424.

[0175] Further, in a case where the operation condition items are notinputted as the result of judgment at the step S420, it goes to stepS426 and judges whether the required bearing life time L_(D) is inputtedor not. In a case where the required bearing life time L_(D) is notinputted, it goes to step S427, sends a guidance information forpromoting the input of the operation conditions for the required bearinglife time to the user's information processing apparatus and thenreturns to the step S420. In a case if the required bearing life timeL_(D) is inputted, it judges that the user requests for the optimaloperation conditions, goes to step 428 and effects the optimal operationcondition deciding processing.

[0176] In the optimal operation condition determining processing, asshown in FIG. 23, it at first goes to step S429 and sets an assumedvalue as the operation condition.

[0177] The assumed values are set to those values considered appropriatefor necessary values for calculation such as of setting P/C=0.1 as theassumed value for the load exerting on the bearing, setting a value{fraction (1/10)} for the allowable number of rotation as the assumedvalue for the number of rotation of the bearing and setting SUJ2 as theassumed value for the bearing material.

[0178] Then, it goes to step S430, calculates the dynamic equivalentload P, the maximum rolling element load Q_(max), the contact ellipsearea S (μm²), the standardized foreign substance diameter(d_(debris)/{square root}{square root over ( )}S), and the lifecorrection coefficient a_(xyz), in the same manner as the processingconducted by the life predicting device of the first embodimentdescribed above based on each of the assumed values and the bearingdynamic rated load C and the bearing static rated load C₀ based on thebearing number, calculates the correction rated life L_(nm) basedthereon and then goes to step 431.

[0179] At the step S431, it judges whether the calculated correctionrated life L_(nm) is, for example, within ±10% of the required bearinglife time L_(D). In a case of: L_(D)×0.9≦L_(nm)≦L_(D)×1.1, it judgesthat the assumed operation conditions are optimal conditions, goes tostep S431, sends the display information for the optimal conditiondisplay screen for displaying the optimal operation conditions to auser's information processing device, then conducts the display andsends the display screen information for displaying the delivery timeand the delivery cost of the optimal bearing to the user's informationprocessing device, then ends the sub-routine processing and goes to thestep S424 of FIG. 20.

[0180] Further, in a case where the result of judgment at the step S431shows: L_(nm)<L_(D)×0.9 or L_(nm)>L_(D)×1.1, it goes to step S433,changes the assumed values for the operation conditions to thepreviously set next assumed values and then goes to the step S430.

[0181] Now referring again to the FIG. 20, in a case if the result ofjudgment at the step S419 shows that the bearing number is not inputted,it goes to step S434, judges whether the operation conditions describedabove are inputted or not. In a case where the operation conditions areinputted, it goes to step 435, and judges whether the required bearinglife time L_(D) is inputted or not. In a case if the required bearinglife time L_(D) is inputted, it judges that the user requires selectionfor the optimal bearing, goes to step 436 and executes the optimalbearing determining processing.

[0182] In the optimal bearing determining processing, as shown in FIG.24, it at first refers to the bearing type at step S437 and assumes thebearing number 6206 for the deep groove ball bearing or the bearingnumber 7206 for the angular ball bearing in a case of a standard bearingof large bearing production amount, for example, a radial ball bearing,the bearing number NU206 for the cylindrical roller bearing in a case ofthe radial roller bearing, or the bearing number HR30206 for the taperedroller bearing in a case of the radial roller bearing, assuming thebearing number 51306 for the thrust ball bearing in the case of thethrust ball bearing, and assuming the bearing number 29420 for thethrust self-aligning roller bearing in a case of the thrust rollerbearing.

[0183] Then, it goes to step S438, calculates the dynamic equivalentload P, the maximum rolling element load Q_(max), the contact ellipsearea (μm²), the standardized foreign substance diameter(d_(debris)/{square root}{square root over ( )}S), and the lifecorrection coefficient a_(xyz) in the same manner as the processingconducted by the life predicting device of the first embodimentdescribed above based on the assumed bearing number and the operationconditions, calculates the correction rated life L_(nm) based on themand then goes to step S439.

[0184] At the step S439, it judges whether the calculated correctionrated life L_(nm) is, for example, within ±10% of the inputted requiredbearing life time L_(D) and, in a case of: L_(D)×0.9≦L_(nm)≦L_(D)×1.1,judges that the assumed bearing number is the optimal condition, goes tostep S440, displays the optimal bearing number, sends the optimalbearing selection display screen information for displaying the deliverytime and the delivery cost for the optimum bearing to the user'sinformation processing device and then goes to the step S424.

[0185] Further, in a case where the result of the judgment at the stepS439 shows: L_(nm)≦L_(D)×0.9 or L_(nm)≧L_(D)×1.1, it goes to step S441,changes the assumed bearing number to a larger or smaller value and thenreturns to the step S438.

[0186] Referring again to FIG. 20, in a case where the result ofjudgment at step S434 shows that the operation conditions are notinputted, it goes to step S442, sends a guidance information ofpromoting input of the bearing number or the operation conditions to theuser's information processing device and then returns to the step S419.Further, in a case where the result of judgement at the step S435 showsthat the required bearing life time L_(D) is not inputted, it goes tostep S443, sends a guidance information of promoting input for thebearing number or the required bearing life time L_(D) to the user'sinformation processing device and then returns to the step S419.

[0187] Then, the operation of the rolling bearing selection device is tobe explained.

[0188] Now, when a user accesses by way of the internet 200 to the WWWserver 202, the user registration input screen for inputting the user'saccount information and password are at first displayed and the bearingselection processing can be executed on the user registration inputscreen in a case of a user already registered. However, in a case of auser who is not yet registered, user registration is conducted byinputting predetermined items on the user registration screen, by whichthe user account information and password are set and the bearingselection processing is executed.

[0189] In the bearing selection processing, the bearing species inputscreen shown in FIG. 21 is displayed, the essential input item, i.e.,whether it is a ball bearing or a roller bearing is selected on thebearing species input screen, and it is selected for the radial bearingor the thrust bearing. Since the row designation is an optionalselection item, it not necessary for designation.

[0190] Then, at the instance the selection for the essential items hasbeen completed, when the next button 216 is selected, an input screenfor input of the desired delivery date and the desired cost is displayedand one or both of the desired delivery date and the desired cost areinputted in a case where they are necessary and the screen is skippedwhen they are not necessary.

[0191] Then, a specification information input screen shown in FIG. 22is displayed. In a case where the bearing such as a deep groove rollingbearing, an angular ball bearing, a cylindrical roller bearing, aself-aligning roller bearing, or the like is determined on thespecification information input screen and where the correction ratedlife L_(nm) is intended to know for the bearing for which the bearingnumber is determined, at least the load P/C exerting on the bearing, thenumber of rotation of the bearing and the mixed foreign substancediameter as the essential input items are inputted. In a case where themixed foreign substance diameter is not inputted, a general or averageforeign substance diameter is set. Further, in a case where the bearingmaterial is not inputted, SUJ2 is set.

[0192] When the input for the operation conditions has been completedand when the calculation executed button 222 is selected, it executesthe same computation as by the life predicting device of the firstembodiment described above to calculate the dynamic equivalent load P,the maximum rolling element load Q_(max), the contact ellipse area S(μm²), the standardized foreign substance diameter (d_(debris)/{squareroot}{square root over ( )}S), and the life correction coefficienta_(xyz), calculates the correction rated life L_(nm) based thereon andoutputs the calculated correction rated life L_(nm) to the display 3 orthe printer 6.

[0193] Further, in a case where it is intended to know the optimaloperation conditions, a bearing number is inputted, and the requiredbearing life time L_(D) is inputted on the specification informationinput screen of FIG. 22.

[0194] In this case, when the required bearing life time L_(D) isinputted as “50,000 hr” for the bearing number “6306”, for example, andthe calculation execute button 222 is selected, an assumed value P/C=0.1(P=2670N) is set as the load P/C exerting on the load bearing, 5000 rpmis set as the assumed value for the number of rotation of the bearingand a general or average value is set as the assumed value for the mixedforeign substance diameter.

[0195] When the same life calculation processing as in the first Exampleis conducted based on the conditions, concrete values are calculated forthe dynamic equivalent load P, the maximum rolling element load Q_(max),the contact ellipse area S (μm²), the value for (d_(debris)/{squareroot}{square root over ( )}S), and the life correction coefficienta_(xyz), and a concrete value for the correction rated life L_(nm) iscalculated based thereon.

[0196] Then, the correction rated life L_(nm) and the required bearinglife time L_(D) are compared and the predicting computation is conductedagain till the correction rated life L_(nm) satisfies the requiredbearing life time L_(D). Then, if it is satisfied, the correction ratedlife L_(nm) and the bearing number are displayed, and an answer screendisplaying the estimated sum and the delivery time for the bearing isdisplayed on the display 3.

(4) Other Embodiments

[0197] In the embodiments described above, while description has beenmade to a case where the life correction coefficient a_(xyz) has onlythe mixed foreign substance diameter d_(debris) as the variable, butthis is not limitative for example, computation is conducted fordetermining the life correction coefficient a_(xyz) by using variablessuch as fatigue limit load Pu, lubrication state (kinetic viscosity) κand environment coefficient (contamination degree of lubricant) a_(c) inaccordance with the proposal of ISO 281 in February, 2000, and theportion for the computation processing of the environmental coefficient(contamination degree of lubricant) a_(c) is conducted by using themixed foreign substance diameter d_(debris) by the computation describedabove by applying the present invention.

[0198] Further, in the foregoing embodiment, while description has beenmade to a case of the ball bearing setting the load index p at 3, thisis applicable also to a roller bearing setting the load index as:p=10/3. This is applicable also in the same manner as in the embodimentdescribed above by determining the contact ellipse area (bearingdimension specification) and working condition (load, average mixedforeign substance diameter, etc.).

[0199] Further, in the foregoing embodiments, while the contact ellipsearea S (μm²) is determined by using the Herz's elastic contact theory,the contact ellipse area may be determined by using other theories orempirical formulas.

[0200] Further, in the embodiments described above, while thestandardized foreign substance diameter (d_(debris)/{square root}{squareroot over ( )}S) as the standardized characteristic quantity iscalculated defining the typical dimension for the portion of the bearingin contact with the mixed foreign substance as {square root}{square rootover ( )}S and the characteristic quantity showing the size of the mixedforeign substance as the diameter d_(debris) thereof and the lifecorrection coefficient a_(xyz) is obtained based on the calculatedstandardized foreign substance diameter (d_(debris)/{square root}{squareroot over ( )}S), this is not limitative. That is, the life correctioncoefficient a_(xyz) is obtained, for example, by determining the value αfor the ratio using the dimension for other portion as the typicaldimension for the portion of the bearing to be in contact with the mixedforeign substance or using other dimension capable of showing thecharacteristic of the foreign substance as the characteristic quantityof the mixed foreign substance thereby obtaining the coefficientaccording to the determined value α for the ratio.

[0201] Further, the standardized foreign substance diameter is definedas a dimension value by dividing d_(debris) as the characteristicquantity showing the size of the mixed foreign substance by {squareroot}{square root over ( )}S as the typical dimension for the portion incontact with the mixed foreign substance, but this is not limitative.For example, the value a for the ratio may be a reciprocal of thestandardized foreign substance diameter or may be a dimensional value.

[0202] Further, in the embodiments described above, while the empiricalformula (8) is obtained assuming the evaluation value coefficient as a₁,the empirical formula may be determined also by other evaluation valuecoefficient a₁ in the same manner. In this case, the empirical formulaecan be determined corresponding to plural evaluation value coefficientsa₁ and variation for the selection of empirical formulae usable by theuser can be increased for instance. In this case, in the secondembodiment described above, for example, the user can obtain thecorrection rated life L_(nm) based on the optimal empirical formula inaccordance with the working conditions, etc.

[0203] Further, in the embodiment described above, while description hasbeen made to a case of executing the program by using a personalcomputer, it is not limitative but it may be executed also by usingother information processing terminals.

[0204] Further, in the embodiment described above, while description hasbeen made to a case of installing the bearing selection program in theWWW server 202 but this is not limitative. A bearing selection programmay be installed to a server connected with a local area network and aninformation processing terminal such as a personal computer may takeaccess by way of the local area network server.

[0205] Further, in the embodiment described above, while description hasbeen made to a case of conducting user registration by the WWW server202 but it is not limitative. User registration may also be conducted byusing postal mailing or facsimile.

[0206] Further, in the embodiment described above, while description hasbeen made to a case of installing the bearing selection applicationprogram in the hard disk of the WWW server 202, this is not limitative.It may be stored into memory medium such as a compact disk (CD) oropto-magnetic disk (MO) other than the hard disk and carried about, ormay be installed to other information processing devices.

[0207] According to the present invention, in a life predicting methodfor a rolling bearing for conducting life prediction of a rollingbearing specified such that a basic dynamic rated load C and a basicstatic rated load C₀ can be calculated, since the rated correction lifeL_(nm) of a rolling bearing at a reliability factor a₁ is calculatedaccording to:

L _(nm) =a ₁ ×a _(xyz)×(C/P)^(p)

a _(xyz) ∝f(α)

[0208] where P represents an equivalent load, p represents a load index,a_(xyz) represents a life correction coefficient, and α represents aratio between a typical dimension for a portion of a bearing to be incontact with mixed foreign substance and a characteristic quantityshowing the size of the mixed foreign substance, the live correctedcoefficient a_(xyz) can be set in accordance with the characteristicquantity showing the size of the mixed foreign substance and, further,since the value a for the ratio with respect to the typical dimensionfor the portion of the bearing in contact with the mixed foreignsubstance is used for the setting thereof, the life correctioncoefficient a_(xyz) can be set in accordance with the mixed foreignsubstance not depending on the size of the bearing. Thus, the life canbe predicted at a improved accuracy for the correction rated life.

[0209] Further, since the value a for the ratio is calculated accordingto:

α=d/{square root}{square root over ( )}S

[0210] where {square root}{square root over ( )}S represents the typicaldimension assuming a typical diameter of the mixed foreign substance asd, and a contact ellipse area in the bearing as S, the life correctioncoefficient a_(xyz) can be set by determining the value α for the ratiousing the contact ellipse area in the bearing and by the determinedvalue α for the ratio.

[0211] Further, since the function f has the viscosity ratio κ of thelubricant, the fatigue limit load Pu and the contamination factor a_(c)as variants, and the contamination a_(c) has the value α for the ratioas a variant, the present application is applicable also in a case ofdetermining the correction rated life based on the life correctioncoefficient a_(xyz) having the lubricant viscosity ratio κ, the fatiguelimit load Pu and the contamination degree coefficient a_(c) as variantsproposed by ISO 281 in February, 2000.

1. A method of conducting life prediction of a rolling bearing such thata basic dynamic rated load C and a basic static rated load C₀ can becalculated, comprising calculating the rated correction life L_(nm) of arolling bearing at a reliability coefficient a₁ according to therelationship: L _(nm) =a ₁ ×a _(xyz)×(C/P)^(p) a _(xyz) ∝f(α) where Prepresents an equivalent load, p represents a load index, a_(xyz)represents a life correction coefficient, and α represents a ratiobetween a typical dimension for a portion of a bearing to be in contactwith a mixed foreign substance and a characteristic quantity showing thesize of the mixed foreign substance.
 2. A life predicting method for arolling bearing according to claim 1, wherein the ratio α is calculatedaccording to the relationship: α=d/{square root}S where {square root}Srepresents the typical dimension assuming a typical diameter of themixed foreign substance as d, and a contact ellipse area in the bearingas S.
 3. A life predicting method for a rolling bearing according toclaim 1 or 2, wherein the function f is determined based on an empiricalformula obtained by mixing foreign substances having differentcharacteristic quantities with respect to the size respectively.
 4. Alife predicting method for a rolling bearing according to claim 3,wherein the function f has a viscosity ratio κ of a lubricant, a fatiguelimit load Pu and a contamination coefficient a_(c) as variables, andthe contamination a_(c) has the value α for the ratio as a variable. 5.A device for conducting life prediction of a rolling bearing such that abasic dynamic rated load C and a basic static rated load C₀ can becalculated, comprising: a specification information inputting means forinputting specification information containing a basic dynamic ratedload C and a basic static rated load C₀ of the rolling bearing; adynamic equivalent load computation means for computing a dynamicequivalent load based on the specification information inputted by thespecification information inputting means; a reliability setting meansfor setting a reliability coefficient; a typical dimension determiningmeans for determining a typical dimension for a portion of a bearing incontact with mixed foreign substance, a mixed foreign substancecharacteristic quantity inputting means for inputting a characteristicquantity showing the size of the mixed foreign substance; a ratiocomputing means for computing the value for the ratio between thetypical dimension and the characteristic quantity; a life correctioncoefficient setting means for setting a life correction coefficientbased on the value ratio; and a bearing life computation means forcomputing the bearing life based on the reliability coefficient, thelife correction coefficient, the basic dynamic rated load, the dynamicequivalent load and the load index.
 6. A device for conducting lifeprediction of a rolling bearing such that a basic dynamic rated load Cand a basic static rated load C₀ can be calculated, comprising: aspecification information inputting means for inputting specificationinformation containing a basic dynamic rated load C and a basic staticrated load C₀ of the rolling bearing; a dynamic equivalent loadcomputation means for computing a dynamic equivalent load based on thespecification information inputted by the specification informationinputting means; a reliability setting means for setting a reliabilitycoefficient; a typical dimension determining means for determining atypical dimension for a portion of a bearing in contact with mixedforeign substance; a mixed foreign substance characteristic quantityinputting means for inputting a characteristic quantity showing the sizeof the mixed foreign substance; a ratio computing means for computingthe value for the ratio between the typical dimension and thecharacteristic quantity; a life correction coefficient setting means forsetting a life correction coefficient based on the value ratio; abearing life computation means for computing the bearing life based onthe reliability coefficient, the life correction coefficient, the basicdynamic rated load, the dynamic equivalent load and the load index; anda re-computation judging means for judging whether the re-computation ofaligning a desired life is necessary or not when the result ofcomputation of the bearing life computation means does not correspond tothe desired life.
 7. A life predicting device for rolling bearingaccording to claim 5 or 6, wherein the ratio computation means obtainsthe value for the ratio by dividing the typical diameter of the mixedforeign substance with the typical dimension as the square root for thecontact ellipse area.
 8. A life predicting device for rolling bearingaccording to claim 5 or 6, wherein the life correction coefficientsetting means sets a life correction coefficient obtained bysubstituting the value for the ratio in the empirical formula obtainedby mixing the foreign substance having different characteristicquantities respectively regarding the size in the bearing.
 9. A lifepredicting device for rolling bearing according to claim 5 or 6, whereinthe life correction coefficient setting means sets the life correctioncoefficient with reference to a viscosity ratio of a lubricant, afatigue limit load and a contamination degree coefficient which changesdepending on the value for the ratio.
 10. A rolling bearing selectiondevice using a life prediction device for a rolling bearing comprising abearing species inputting means for inputting a bearing species desiredby a user; a specification information inputting means for inputtingnecessary specification information other than the necessaryspecification information required by the user from necessaryspecification information containing a basic dynamic rated load C and abasic static rated load C₀ of a rolling bearing; a specificationinformation assuming means for comparing the required specificationinformation and the necessary specification information inputted by thespecification information inputting means thereby assuming thenot-inputted specification information; a life predicting device for arolling bearing according to claim 6 conducting bearing life predictingcomputation based on the specification information inputted by thespecification information inputting means and the specificationinformation assumed by the specification information assuming means; ajudging means for judging whether the result of computation by the lifepredicting device can satisfy the specification information inputted bythe specification information inputting means or not; a specificationinformation presenting means for presenting the specificationinformation set by the specification information assuming means when theresult of the judgment by the judging means can satisfy thespecification information; and a re-computing means for changing thespecification information assumed by the specification informationassuming means and conducting re-computation by the life predictingdevice for the rolling bearing when the result of the judgment of thejudging means can not satisfy the specification information.
 11. Arolling bearing selecting device according to claim 10, wherein thespecification information inputting means, the specification informationassuming means, the life predicting device for the rolling bearing, thejudging means, the specification information presenting means and there-computation means are adapted accessible by way of an internet.
 12. Arolling bearing selecting device according to claim 11, comprising auser registration accepting means for accepting user registration by wayof an internet, in which only a user registered by the user resisteraccepting means is granted accesss by way of the internet to thespecification information inputting means, the specification informationassuming means, the life predicting device for the rolling bearing, thejudging means, the specification information presenting means and there-computation means.
 13. A rolling bearing selecting device accordingto claim 11 or 12, which is adapted such that it can select a languageused in the specification information inputting means, the specificationinformation assuming means, the life predicting device for the rollingbearing, the judging means, the specification information presentingmeans and the re-computation means.
 14. A rolling bearing selectingdevice according to any one of claims 10 to 12, wherein thespecification information presenting means is adapted to conduct any oneof presentation for the life prediction of the rolling bearing,presentation of an optimal bearing and presentation of optimal workingconditions.
 15. A rolling bearing selecting device according to any oneof claims 10 to 12, comprising a delivery information presenting meanspresenting at least one of the delivery date and the estimated sum forthe rolling bearing based on the specification information presented bythe specification information presenting means.
 16. A program in amemory medium storing a life predicting program for predicting life of arolling bearing such that a basic dynamic rated load C and a basicstatic rated load C₀ can be calculated, comprising descriptions forexecuting, by a computer; inputting specification information containingthe basic dynamic rated load C and the basic static rated load C₀ of therolling bearing; computing a dynamic equivalent load based on thespecification information; determining a typical dimension for a portionof the bearing in contact with mixed foreign substance; inputting acharacteristic quantity indicating the size of the mixed foreignsubstance; computing the value for the ratio between the typicaldimension and the characteristic quantity; setting the life correctioncoefficient based on the value for the ratio; and computing the bearinglife based on the reliability coefficient, the life correctioncoefficient, the basic dynamic rated load, the dynamic equivalent load,and a load index.
 17. A program in a memory medium storing a lifepredicting program for predicting life of a rolling bearing such that abasic dynamic rated load C and a basic static rated load C₀ can becalculated, comprising descriptions for executing, by a computer;inputting specification information containing the basic dynamic ratedload C and the basic static rated load C₀ of the rolling bearing;computing a dynamic equivalent load based on the specificationinformation; determining a typical dimension for a portion of thebearing in contact with mixed foreign substance; inputting acharacteristic quantity indicating the size of the mixed foreignsubstance; computing the value for the ratio between the typicaldimension and the characteristic quantity; setting the life correctioncoefficient based on the value for the ratio; and computing the bearinglife based on the reliability coefficient, the life correctioncoefficient, the basic dynamic rated load, the dynamic equivalent loadand the load index; and judging whether re-computation for aligning adesired life in a case is necessary or not when the result ofcomputation for the bearing life does not correspond to the desiredlife.
 18. A program in a memory medium storing a bearing selectingprogram for selecting a rolling bearing in accordance with thespecification required by a user, comprising description for executing,by a computer; inputting a bearing species required by a user; inputtingnecessary specification information other than the requiredspecification information required by the user from the necessaryspecification information containing a basic dynamic rated load C and abasic static rated load C₀ of a rolling bearing; comparing the requiredspecification information and the necessary specification informationthereby assuming the not inputted specification information; predictinglife by using the life predicting program according to claim 16 based onthe required specification information and the assumed specificationinformation other than that described above, judging whether the resultof the life prediction can satisfy the required specificationinformation or not; presenting the assumed specification information asthe bearing selection information when the result of the life predictioncan satisfy the required specification information, and changing theassumed specification information in a case when the result of the lifeprediction can not satisfy the required specification information andconducting re-computation by the life predicting program.
 19. Anenvironment coefficient determining method for determining anenvironment coefficient for the life correction coefficient used in thebearing life calculation, wherein the environment coefficient isdetermined at least by the ratio between a typical dimension for aportion of a bearing in contact with mixed foreign substance and acharacteristic quantity indicating the size of the mixed foreignsubstance.
 20. An environment coefficient determining method accordingto claim 19, wherein the value for the ratio is calculated by:α=d/{square root}S where {square root}S represents the typicaldimension, assuming a typical diameter of the mixed foreign substance asd, and a contact ellipse area in the bearing as S.
 21. A life predictingdevice for rolling bearing according to claim 7, wherein the lifecorrection coefficient setting means sets a life correction coefficientobtained by substituting the value for the ratio in the empiricalformula obtained by mixing the foreign substance having differentcharacteristic quantities respectively regarding the size in thebearing.
 22. A life predicting device for rolling bearing according toclaim 7, wherein the life correction coefficient setting means sets thelife correction coefficient with reference to a viscosity ratio of alubricant, a fatigue limit load and a contamination degree coefficientwhich changes depending on the value for the ratio.
 23. A lifepredicting device for rolling bearing according to claim 8, wherein thelife correction coefficient setting means sets the life correctioncoefficient with reference to a viscosity ratio of a lubricant, afatigue limit load and a contamination degree coefficient which changesdepending on the value for the ratio.